Ramautar J R, Kok A, Ridderinkhof K R
Department of Psychology, University of Amsterdam, Roetersstraat 15, 1018 WB Amsterdam, The Netherlands.
Brain Cogn. 2004 Nov;56(2):234-52. doi: 10.1016/j.bandc.2004.07.002.
The aim of this study was to examine the effects of frequency of occurrence of stop signals in the stop-signal paradigm. Presenting stop signals less frequently resulted in faster reaction times to the go stimulus and a lower probability of inhibition. Also, go stimuli elicited larger and somewhat earlier P3 responses when stop signals occurred less frequently. Since the amplitude effect was more pronounced on trials when go signals were followed by fast than slow reactions, it probably reflected a stronger set to produce fast responses. N2 and P3 components to stop signals were observed to be larger and of longer latency when stop signals occurred less frequently. The amplitude enhancement of these N2 and P3 components were more pronounced for unsuccessful than for successful stop-signal trials. Moreover, the successfully inhibited stop trials elicited a frontocentral P3 whereas unsuccessfully inhibited stop trials elicited a more posterior P3 that resembled the classical P3b. P3 amplitude in the unsuccessfully inhibited condition also differed between waveforms synchronized with the stop signal and waveforms synchronized with response onset whereas N2 amplitude did not. Taken together these findings suggest that N2 reflected a greater significance of failed inhibitions after low probability stop signals while P3 reflected continued processing of the erroneous response after response execution.
本研究的目的是检验停止信号范式中停止信号出现频率的影响。较少频率地呈现停止信号会导致对启动刺激的反应时间更快，抑制概率更低。此外，当停止信号出现频率较低时，启动刺激会引发更大且稍早的P3反应。由于在启动信号后快速反应比慢速反应的试验中幅度效应更明显，它可能反映了产生快速反应的更强准备状态。当停止信号出现频率较低时，观察到对停止信号的N2和P3成分更大且潜伏期更长。这些N2和P3成分的幅度增强在未成功的停止信号试验中比在成功的停止信号试验中更明显。此外，成功抑制的停止试验引发额中央P3，而未成功抑制的停止试验引发更靠后的P3，类似于经典的P3b。在未成功抑制的条件下，与停止信号同步的波形和与反应开始同步的波形之间的P3幅度也有所不同，而N2幅度没有差异。综合这些发现表明，N2反映了低概率停止信号后抑制失败的更大重要性，而P3反映了反应执行后错误反应的持续处理。
